Fix best-fit viewer bounds for angled pairs

OpenNest.Tests/BestFit/BestFitResultFrameTests.cs

@@ -0,0 +1,72 @@
+using OpenNest.Engine;
+using OpenNest.Engine.BestFit;
+using OpenNest.Geometry;
+using OpenNest.Math;
+using OpenNest.Shapes;
+
+namespace OpenNest.Tests.BestFit;
+
+public class BestFitResultFrameTests
+{
+    [Fact]
+    public void BuildCanonicalParts_NonAxisAlignedPairNormalizesActualBounds()
+    {
+        var drawing = new TShape { Width = 10, Height = 8 }.GetDrawing();
+        var canonical = CanonicalFrame.AsCanonicalCopy(drawing);
+
+        var result = EvaluateOffsetPair(canonical, new Vector(40, 30));
+
+        Assert.True(IsNonAxisAligned(result.OptimalRotation),
+            $"Expected a non-axis-aligned result, got {Angle.ToDegrees(result.OptimalRotation):F2} degrees.");
+
+        var parts = result.BuildCanonicalParts();
+        var bounds = result.GetCutBounds(parts);
+
+        Assert.Equal(0, bounds.Left, 3);
+        Assert.Equal(0, bounds.Bottom, 3);
+        Assert.Equal(result.BoundingWidth, bounds.Length, 2);
+        Assert.Equal(result.BoundingHeight, bounds.Width, 2);
+    }
+
+    [Fact]
+    public void BuildSourceParts_RebindsCanonicalResultToRotatedSourceDrawing()
+    {
+        var drawing = new TShape { Width = 10, Height = 8 }.GetDrawing();
+        drawing.Program.Rotate(Angle.ToRadians(30), drawing.Program.BoundingBox().Center);
+        drawing.RecomputeCanonicalAngle();
+
+        var canonical = CanonicalFrame.AsCanonicalCopy(drawing);
+        var result = EvaluateOffsetPair(canonical, new Vector(40, 30));
+
+        var parts = result.BuildSourceParts(drawing);
+        var bounds = result.GetCutBounds(parts);
+
+        Assert.All(parts, p => Assert.Same(drawing, p.BaseDrawing));
+        Assert.Equal(0, bounds.Left, 3);
+        Assert.Equal(0, bounds.Bottom, 3);
+        Assert.False(parts[0].Intersects(parts[1], out _));
+    }
+
+    private static BestFitResult EvaluateOffsetPair(Drawing drawing, Vector offset)
+    {
+        var candidate = new PairCandidate
+        {
+            Drawing = drawing,
+            Part1Rotation = 0,
+            Part2Rotation = System.Math.PI,
+            Part2Offset = offset,
+            Spacing = 0.25
+        };
+
+        return new PairEvaluator().Evaluate(candidate);
+    }
+
+    private static bool IsNonAxisAligned(double angle)
+    {
+        var normalized = Angle.NormalizeRad(angle);
+        var nearestQuadrant = Angle.HalfPI * System.Math.Round(normalized / Angle.HalfPI);
+        var delta = System.Math.Abs(normalized - nearestQuadrant);
+        delta = System.Math.Min(delta, Angle.HalfPI - delta);
+        return delta > Angle.ToRadians(1);
+    }
+}